There are several things we can do to improve the sustainability of our world and slow down climate change. The three things I advocate for the most are: switching to plant-based diet (comes with the hugely beneficial side effect of lowering immensely cruel animal suffering); expand low-carbon energy (mainly nuclear power) to durably displace fossil fuels; rethink transportation to lower car use and private ownership.

But one thing I have no answer to is construction. That's because concrete is the foundation of modern infrastructure but comes with a big environmental burden. In order to produce it you need to mine sand, a lot of it in fact (it is actually the most mined natural resource), and its production releases carbon dioxide in the atmosphere for inherent chemistry reasons (carbon contained in the mined material is released when cement is made). The sheer scale of mining means that a lot of places will be damaged by human activity, and combined with the fact concrete grade sand is found in areas you'd expect to be home of a considerably amount of biodiversity like rivers and beaches, its environmental impact is quite huge.

So what could be the future for sustainable construction? Of course I'm not asking for something with zero environmental impact because there's no such thing, but something that at least doesn't release greenhouse gases in the atmosphere even of powered by clean energy, and preferably with less environmental impact from mining.

Appeal to nature: the strange belief that what is perceived as "natural" is necessarily safer, more effective or morally superior compared to what isn't.

I think you have your chemistry mixed up a bit, the CO2 comes from the heated calcium carbonate used to make cement, which is a component of most concrete (it's what binds the aggregates, like sand, together). I don't think mining the sand or rocks for aggregate is really an issue, but I could be wrong. I can see how it might be a local habitat issue, but I don't think that's what's contributing to climate change.

Unfortunately it's very hard to completely replace concrete. The best we can probably do is use more wood and less concrete/steel (except for the foundations, and connecting the wood together). Cobb is another potentially good option (also made with sand) for certain application, but like wood it's no good for ground contact.

Buildings in the 1-4 story range can be made pretty easily with wood, and it would make a lot of sense to focus on bringing the majority of human infrastructure up to that height with wood (and maybe some application of other building materials, particularly for the ground floor).

There are many different building materials for residential houses, although other materials are difficult for say skyscrapers. George Monbiot has a section on building materials in his book Heat, which is about climate change.

We can also consider building from recycled materials, building smaller, more compact buildings and replacing existing buildings less often (counterpoint: if a building is poorly insulated and this is difficult to fix, this may not make sense from a CO2 standpoint). We could also increase working from home and shared living spaces where areas such as the computer room and laundry room are shared between multiple houses.

Awareness also needs to be raised - this isn't something people think of. I'm surprised anyone bought this up.

building smaller, more compact buildings and replacing existing buildings less often (counterpoint: if a building is poorly insulated and this is difficult to fix, this may not make sense from a CO2 standpoint). We could also increase working from home and shared living spaces where areas such as the computer room and laundry room are shared between multiple houses.

Definitely, we more need to think about building smarter and optimizing space. Tiny house strategies applied to multi-family units would be amazing. The solution is not to put everybody in tiny houses on steel trailers that have a huge surface area and are more difficult to heat/cool per square foot and ultimately take up more land because they need driveways and can't be stacked.

I think you have your chemistry mixed up a bit, the CO2 comes from the heated calcium carbonate used to make cement, which is a component of most concrete (it's what binds the aggregates, like sand, together).

And I think you misunderstood my post because the chemistry of cement production was exactly was I was referring to in my post (understand concrete production as indirectly releasing CO2 due to inherent chemistry reasons, because cement is needed to make it).

Buildings in the 1-4 story range can be made pretty easily with wood, and it would make a lot of sense to focus on bringing the majority of human infrastructure up to that height with wood (and maybe some application of other building materials, particularly for the ground floor).

Might be interesting to use more wood since it is not as energy intensive as concrete and steel production and the fact it stores air carbon. Managed forestry land stores less carbon than natural forests, but since at some point natural forests are mature enough and don't absorb more CO2 than they emit anymore, while this state can be reset with managed forestry land, the later can store more carbon on the long term, although for that the logged trees need to not release their CO2 back into the atmosphere. If wood used for construction ends up as a biomass energy source then it can't be called a carbon sink, so timber from demolition waste should be recycled rather than being burned as much as possible. I'm also worried about the scaling up of timber production that might cause increased land use, especially considering that trees grow very slowly, although the displacement of energy intensive materials and the carbon trapped in construction timber might make it worth it from a climate perspective.

A way to increase timber production while not increasing the stress on wood demand too much might be to popularize bidets as a way to displace toilet paper. It also comes with a lot of other benefits, like lower electricity use, better hygiene and lowering the risks of clogging plumbing lines. Using water to wash directly is also more efficient than using water to grow trees and using their paper to clean up; imo toilet paper should only be considered as the first option in areas with water shortages (as the water used to produce it would come from an area where water is not scarce). I also wonder if trees grown for biomass energy could be instead used for timber, which I think is a better use as I'm highly skeptical of the environmental pertinence of growing biomass from trees for energy as anything but maybe a waste product (although trees for timber and energy are maybe not the same kind).

There are however concerns with timber as a construction material. It can make houses built with it more likely to catch fire, and I know I would personally live in a home that's as fireproof as possible; timber can also rot or be attacked by termites. I'm pretty sure wood can be treated to mitigate those problems, but I doubt it will be as good as a building made of mostly steel and concrete.

Appeal to nature: the strange belief that what is perceived as "natural" is necessarily safer, more effective or morally superior compared to what isn't.

With modern construction, fire isn't a big issue. That's why we use things like sheetrock, and building code requires fire blocks.
Likewise, you just keep it dry and use some basic treatment, and rot and bug issues can be avoided. Wood is a good material as long as you use it smart, it can last hundreds of years.